def select_pipes(pipes):
    """
    Select pipes which have the same load as the first pipe of the dataframe
    *pipes*.

    Parameters
    ----------
    pipes: DataFrame
        Dataframe of the TST pipes.

    Returns
    -------
    DataFrame
        Dataframe of the selected pipes (same load as the first pipe).
    """
    load = pipes.at[0, 'load']
    pipes_selection = pipes.loc[pipes['load'] == load].copy()
    return pipes_selection
